1. Field of the Invention
The present invention generally relates to cryptography, and more specifically to a method and apparatus for sending a message securely over an insecure channel.
2. Related Art
In general, data transmitted on insecure channels can potentially be intercepted and examined by unknown third parties (intruders). There is a general recognised need in the industry to send messages securely (i.e., an intruder cannot decipher a message encoded in the transmitted data) even on such insecure channels.
Encryption technologies are often employed to transmit messages securely over an insecure channel. In general, a sender encrypts a message to generate cipher data, and send the cipher data on the insecure channel. An intruder can only decipher the message from the cipher data using a decryption technique consistent with the encryption technique.
One common encryption/decryption technique combination is based on public key infrastructure (PKI), in which a receiver generates a key pair (private key and public key) using known mathematical approaches. The public key is then communicated to any of the potential senders.
A sender encrypts a message using the public key and sends the resulting cipher data on an insecure channel. In most practical scenarios, only a receiver having access to the private key can recover the message from the cipher data. Accordingly, messages may be sent in a secure manner, even on insecure channels.
One problem with the keys based approach of above is that security of the messages depends on intruders not having access to the private key (or any other key required for decryption). Once the private key is compromised, an intruder may be able to decipher the messages with ease. As the key pair may not change for a long time, the approach is particularly susceptible to compromise of the private key, and thus of security.
What is therefore needed is a method and apparatus which enables messages to be sent securely on insecure channels, while addressing one or more of the requirements noted above.
In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit(s) in the corresponding reference number.